Optimization of highly microporous activated carbon preparation from Moso bamboo using central composite design approach

•Highly microporous activated carbons were prepared from Moso bamboo.•Increasing activation temperature/time increased surface area and microporosity.•Over-gasification reduced surface area of bamboo activated carbons.•Optimal activation time and temperature were acquired via CCD approach.•Optimal temperature can be set at 835 °C ± 5% with activation time of 1.75 h ± 30%.

Highly microporous activated carbons were prepared from Moso bamboo (Phyllostachys pubescens) using physical (steam) and chemical (KOH) activation. Increasing activation temperature and time was shown to increase the surface area and microporosity of activated carbons, which were further reduced due to over-gasification. Development of micropores was clearly observed based on N2 adsorption isotherms. Steam activation temperature at 800 °C and activation time of 2.25 h can achieve large total surface area (SBET) of 1135 m2/g and micropore volume of 0.521 cm3/g. For KOH activation (KOH/char mass ratio = 2), the 800 °C activation temperature and 2.25 h activation time resulted in SBET of 1673 m2/g and micropore volume of 0.847 cm3/g. For KOH activation with a KOH/sample mass ratio = 4, 870 °C activation temperature and 1.27 h activation time enhanced SBET to 2527 m2/g and micropore volume to 0.96 cm3/g. Central-composite design approach appeared to successfully acquire the optimal activation conditions, which can be set at 835 °C ± 5% with an activation time of 1.75 h ± 30% for both physical and chemical activation. The optimal conditions could cause the resulting bamboo activated carbons with the greatest SBET and sufficient microporosity.